Power wrench



Sept. 22, 1970 o. v. NORTHCUTT POWER WRENCH Original Filed 001:; 24,1965 FIG.*3

FIG.2 53

'INVENTOR OREN V. NORTHCUTT WWW ATTORNEY United States Patent 3,529,498POWER WRENCH Oren V. Northcutt, Dallas, Tex., assignor of one-half tJames E. Northcutt, Dallas, Tex. Continuation of application Ser. No.684,556, Nov. 20, 1967, which is a continuation of application Ser. No.504,670, Oct. 24, 1965. This application Feb. 5, 1969, Ser. No. 800,340

Int. Cl. B25b 21/00 US. C]. 81-54 13 Claims ABSTRACT OF THE DISCLOSURE Awrench including a shaft rotatable by a motor and having a stud at oneend thereof parallel but eccentrically disposed with respect to thelongitudinal axis of the shaft. A ball is carried by a ratchet head andhas an opening eccentric with respect to a diameter of the ball intowhich the stud rotatably projects. Rotation of the shaft causesoscillation of the ratchet head with a force and stroke dependent uponthe load imposed on the ratchet head by a driven wrench member. Aresistive force may be provided on the driven wrench member in order topermit ratchet action to occur even when the wrench drive does not carrya substantial load. The direction of the ratchet action may beselectively changed without changing the direction of rotation of themotor.

This application is a continuation of application Ser. No. 684,556,filed Nov. 20, 1967 which was a continuation of Ser. No. 504,670, filedOct. 24, 1965; both now abandoned.

The present invention relates to power wrenches.

Power wrenches are frequently used. For example, pneumatic wrenches ofthe general type shown in US. Pat. 2,263,736, are used to remove studsfrom engine heads and to remove nuts in a variety of locations. Theconstruction of this type wrench is such, however, that a rathercumbersome structure is disposed coaxially outwardly from the stud ornut being manipulated. In many cases head room is not available topermit such a wrench to operate. Accordingly, effort has been made toprovide a wrench requiring little head room. Exemplary of such a wrenchis that shown in US. Pats. 2,264,012; 2,086,261; and 2,758,569. Whilecertain of the prior art structures have met with a degree of success,the structures are generally complex, rather large, and sometimesunreliable in operation.

An object of the present invention is to provide an efficient, compact,and comparatively simple power wrench of the type that may be driven ina desired direction to remove or set a stud, bolt, or the like.

A further object is to provide such a wrench that may be used in avariety of applications, including the driving of sockets.

Another object is to provide such a wrench that works rapidly when theload is light, yet which is self-regulating to increase the torquedelivered, at reduced speed, when the load becomes heavy.

Yet a further object is to provide a power driven ratchet wrench whichwill ratchet properly even under conditions where no material externalload is being handled by the wrench.

The present invention provides a power wrench which comprises arotatable shaft, motor means for rotating the shaft, an oscillatoryhead, a frame for pivotally carrying the head, means for interconectingthe shaft and ratchet head to oscillate the head when the shaft isrotated, a rotatable wrench drive, and means operably interconnectingthe oscillatory head and wrench drive to cause ice the wrench drive torotate in one direction while the oscillatory head oscillates.

In a preferred embodiment, the axis of rotation of the motor drivenshaft is perpendicular to the axis of rotation of the wrench drive.Moreover, in the preferred embodiment the means for interconnecting theshaft and ratchet head include a stud, parallel but eccentricallydisposed with respect to the axis of rotation of the shaft, and a ballhaving an opening into which the stud projects. Preferably the openingin the ball is eccentric with respect to the balls diameter. The ball iscarried within an arcuate slot, formed in the oscillatory head.

A preferred embodiment further provides a plurality of teeth on theoscillatory head and a pawl which is carried by the wrench drive. Thepawl and teeth are so disposed that the pawl engages the teeth duringthe movement of the teeth in one direction, but is disengaged from themduring their movement in the opposite direction.

Yet aanother provision of a preferred embodiment is means for placing aresistive force on the wrench drive means during the ratchet stroke.This premits ratchet action to occur even when the wrench drive meanscarries no substantial load.

For a more complete understanding of the present invention and forfurther objects and advantages thereof, reference may now be had to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a perspective view of a power wrench in accordance with thepresent invention;

FIG. 2 is a fragmentary partially sectioned side view of the wrench ofFIG. 1,

FIG. 3 is a fragmentary end view of the structure of FIG. 1, with theratchet head 25 removed and the ears 23a and 23b sectioned for clarity;

FIG. 4 is an end view of the crank shaft 31, with the ball means 37assembled thereon in the position of maximum stroke; and

FIG. 5 is a view of the structure shown in FIG. 4, but with the ballmeans 37 rotated into the position of minimum stroke.

Referring now to FIG. 1, therein is illustrated generally at 11 a powerwrench in accordance with the present invention.

The wrench 11 may be powered by a variety of means. However, an airmotor 13 is employed in the embodiment illustrated. To the motor 13 isconnected an air hose 15 through the conduit handle 16. An air controlvalve carried in the conduit-handle 16, is positioned by thumb button 17to admit air to the motor when it is desired that it be actuated. Themotor 13 of the rotary type having a plurality of vanelike membersdriven by air.

If desired, an electric motor may be substituted for the air motor 13.Since essentially any rotary type motor means may be utilized, and sincea host of suitable conventional motors are available, no specific motordetail is illustrated herein.

A lower annular casing 21 extends from the lower portions of the casingof motor 13. On its extremity it carries a yoke 23. The yoke 23comprises spaced apart ear portions 23a and 23b. Ear 23a has formed init a large circular opening. Moreover, ear 23b carries a circularopening, the center of which is aligned with the center of the openingin ear 23a. The opening in ear 23b is considerably smaller than in ear23a.

Ratchet head 25 is carried between the ears 23a and 23b of yoke 23.

A large circular opening is formed through the central portion ofratchet head 25 (see FIG. 2) and a plurality of teeth 27 are disposedabout the entire periphery of the opening.

A shaft 31 is carried within the annular casing 21. An annular bearing33 toward the lower end of the shaft (as viewed in FIG. 2) is providedfor supporting the shaft. Preferably an upper bearing of similarconstruction (not illustrated) is also provided. The shaft 31 has itsdriven end connected to the rotating mechanism of motor 13.

The end of shaft 31 remote from the motor 13 is pro vided with acylindrical projection or stud 35. The longitudinal axis of thiscylindrical projection is parallel to, but displaced from, the axis ofthe shaft 31.

The projection 35 extends into a mating opening which is formed in aball member 37. The axis of this mating opening is preferably offsetfrom the axis of the ball, i.e., it is not concentric with a diameter ofthe ball. The structure and its effect will be discussed at a laterpoint hereinafter.

The ball 37 is carried within a suitable arcuate slot 39 which is formedin the upper regions of the ratchet head 25. The ball 37 may be movedsideways in the arcuate slot 39; however it is retained in position withrespect to movement along any other axis because of the conformance ofthe surface defining the recess with the shape of the ball. Accordingly,movement of the ball in a side-toside direction, as seen in FIG. 2,necessarily carries the ratchet head 25 along with it. Since the ratchethead 25 is constrained to rotate about an axis passing through theopenings in ears 23a and 23b, the ratchet head will rock back-'and-forthas the ball 37 is moved about by rotation of crank 31. It should beappreciated that the thickness of the ratchet head 25 is sufficientlygreater than the diameter of the ball 37 to permit movement of the ballin a direction transverse to the plane of the rocking movement. Thus onrotation of this shaft, the ball member 37 is able to rideback-and-forth within the arcuate slot 39 without striking the sides ofthe ears 23a and 23b.

A wrench drive assembly 41 is carried within the toothsurroundedcircular recessed central portion of ratchet head 25. The drive assembly41 has an enlarged generally cylindrical mid-portion 43' which isdisposed between the ears 23a and 23b of the yoke 23 (see FIG. 3). Thiscylindrical enlarged portion is slotted or recessed along a side orperipheral portion in such a way that spaced apart shoulders 45 and 46are defined. Within the recessed region between the shoulders 45 and 46,a ratchet pawl 47 is disposed. This pawl is movably mounted on a shaft49, one end of which is carried by a recess in the shoulder 45 and theother by a recess in the shoulder 46. Accordingly, the pawl 47 ismounted whereby it can be rocked between two extreme positions.

A plunger 51 is carried by a generally cylindrical member 53 whichpasses through a mating cylindrical cavity coaxial with the center ofthe drive assembly 41. An end of the plunger 51 rides within aplunger-receiving aperture 54 which passes through the member 53. Theaperture 54 is radially directed with respect to member 53 and thecircular array of the set of ratchet teeth 27. A spring is disposedWithin aperture 54 to press adjacent the end of plunger 51 carriedwithin the aperture. Accordingly, the detent is biased outwardly byspring 55. Note that this causes the extending end of the plunger topush against the inner curved portion 57 of the pawl 47.

The plunger 51 may be positioned between two extremes by the rotation ofthe knurled knob 61, which is coaxial and integral with member 53. Asillustrated in FIG. 2, the plunger is at one of these extreme positions.By movement of the knurled knob 61, the plunger can be moved into ananalogous position where it rides adjacent the other end of the innercurved portion 57 of the pawl 47.

Shaft 63 is integral with and extends coaxially outwardly from thecentral portion 43 of wrench drive assembly 41. This shaft passesthrough an opening in the ear 23b (previously referred to) which isshaped to rotatably receive and provide bearing support for it. A socketwrench engaging stud 65 of rectangular cross section is joined to theshaft 63 and extends outwardly from its end. This stud 65 isconventionally shaped to mate with a socket. Note that it is providedwith a conventional springloaded detent 67.

A resilient, fnlsto-conical washer 71 (a so-called Belleville spring)rides on shaft 63 with its opposite ends bearing respectively againstthe side of central portion 43 of wrench drive assembly 41 and of theinside face of the ear 23b of yoke 23. A conventional snap ring 73 iscarried by a suitable groove running about the periphery of shaft 63.The side of this snap ring engages the outer side of ear 23b and retainsthe shaft assembly 41 and its associated parts in position. Note thatthe groove for the snap ring 73 is positioned on shaft 63 a suitabledistance from the side of the central portion 43 of drive assembly 41 tocause the frusto-conical iwasher 71 to be compressed somewhat. Thisprovides a reactive force by the washer against the central portion 43of wrench drive assemb y 41.

Attention is directed to the two sets of teeth 75a and 75b which aredisposed on opposite outer end regions of the pawl 47. It should beappreciated that either set of these teeth may be engaged as desiredwith the teeth 27 on the ratchet head by appropriately positioning theknob 61 to cause plunger 51 to assume an appropriate position to urgethe desired end of the pawl outwardly.

In operation, with the knob 61 rotated to place the teeth 75a of pawl 47into engagement with the teeth 27 of the ratchet head 25, rotation ofshaft 31 causes the crank member 35 to carry the ball 37 about in agenerally circular path, thus resulting in a rocking or side-to-sidemotion of the ratchet head 25. Accordingly, the teeth 27 on the ratchethead oscillate back-to-forth about the center of the circle on whichthey are disposed. As the teeth 27 rotate counterclockwise as viewed inFIG. 2, the pawl 47 is carried along by the mutual tooth engagement tocause it to follow the general rotary path of motion of the ratchethead. Accordingly, the drive assembly which carries the pawl is rotatedcounterclockwise. When the ratchet head 25 rotates in the oppositedirection (i.e., clockwise) the teeth 27 push pawl teeth 75a inwardlyand free of engagement with the teeth 27. Ratchet action results.

As a result of the motion described above, the rocking action impartedby the shaft, crank means, and ball to the ratchet head causes thewrench drive to rotate in one given direction only. Accordingly, thestud 65 Will drive a socket or other engaged member in a single desireddirection of rotation.

When it is desired to reverse the ultimate direction of rotationimparted to the stud 65, it is only necessary to rotate the knob 61 tomove the plunger 51 into springloaded engagement with the oppositeperipheral inner extremity of pawl 47. This causes the teeth on the pawlpreviously out of engagement (teeth 75b as seen in FIG. 2) to be movedinto engagement with the teeth 27. Ratchet action and drive action inthe opposite sense to that previously described will result when theratchet head 25 is moved.

The frictional engagement of the frusto-conical washer 71 and the sideof central member 43 of wrench drive assembly 41 is a significantfeature when the wrench engaging stud 65 is not substantially loaded, aswhen a bolt is turned with little resistance by a socket engaged withthe stud 65. Without such frictional engagement sufiicient resistancewould not be present to cause the pawl teeth to move out of engagementwith the ratchet drive teeth 27 during the ratchet portion of the cyclemade by the ratchet drive. Under this condition, ratchet action wouldnot occur and the stud would oscillate backand-forth. But the frictionalengagement referred to insures that there is suflicient resistance tothe rotation of the wrench drive assembly 41 to cause the pawl teeth tobe moved out of engagement during the ratchet portion of the cycle. Thisinsures ratchet action under all conditions, no matter how light theload on stud 65.

Attention is directed to the relationship between the ball member 37 andthe projection 35 on shaft 31. This relationship is illustrated in FIGS.4 and 5 wherein it is seen that the projection 35 is eccentric withrespect to the axis A passing through the center of shaft 31. It isfurther seen that the opening in ball member 37 which mates with theprojection 35 is offset or eccentric with respect to the axis B whichpasses through the center of ball member 37. Accordingly, the ball mayassume a variety of positions varying between the extremes illustratedin FIGS. 4 and 5. Thus in FIG. 5, the ball is illustrated in a positionsuch that the eccentricity of its opening causes the axis of the ball tobe a maximum distance X with relation to the axis of the shaft 31. Onthe other hand, FIG. 5 illustrates the ball when it is swung into aposition such that its eccentricity causes the distance from the axis ofthe ball to the axis of shaft 31 to be at a minimum value X.

The load which must be handled by the stud member 65 ultimatelydetermines the extent of displacement of the axis of the ball member 37with respect to the axis of the shaft 31. Thus in instances where aheavy load is being handled, the comparatively large forces existingbetween the ratchet head, ball, and projection will cause the ball toassume the shortest displacement possible with respect to the center ofthe axis of the shaft. Thus a short but powerful stroke results where amaximum of force can be transmitted.

On the other hand, when the forces between the ratchet head, ball, andprojection are quite low, as when a bolt is quite easily turned down orwithdrawn, the maximum displacement will exist between the center of theball and the axis of shaft 31. Under these conditions, a long strokewill occur which causes the stud 65 to make the largest possiblemovement, thus withdrawing or driving a bolt or the like quickly. Underthese conditions, the power transmitted is at a minimum although themovement is at a maximum.

Having described the invention in connection with certain specificembodiments thereof, it is to be understood that further modificationsmay now suggest themselves to those skilled in the art and it isintended to cover such modifications.

What is claimed as new is as follows:

1. A power wrench comprising: a rotatable shaft having at one endthereof a stud connected parallel but eccentrically disposed withrespect to the axis of rotation of said shaft, motor means for rotatingsaid shaft, an oscillatory head having an arcuate slot therein, a framefor pivotally carying said head, ball means received by said arcuateslot in said oscillatory head and having an opening eccentric withrespect to a diameter of said ball means for rotatably receiving saidstud, rotation of said shaft causing oscillation of said head with avarying force and length stroke dependent upon the load imposed thereon,a rotatable wrench drive, and means interconnecting said oscillatoryhead and said wrench drive for rotating said wrench drive in a selecteddirection when said head oscillates.

2. The power wrench of claim 1 wherein the axis of rotation of saidshaft and the axis of rotation of said wrench drive are perpendicular.

3. The power wrench of claim 1 wherein said oscillatory head is providedwith a central, generally-circular opening, the center of which is thecenter of rotation of said oscillating head, and wherein the meansoperably interconnecting said oscillatory head and wrench drive havedriving engagement with said oscillatory head along the peripheralsurfaces defining the said opening in said oscillatory head.

4. The power wrench of claim 3 wherein teeth are carried about theperipheral surfaces of said opening in said oscillatory head, andwherein the said means operably interconnecting said oscillatory headand wrench drive comprises pawl means engaging said teeth when saidteeth are moving in one direction, but disengaging therefrom when saidteeth are moving in the other direction.

5. A power wrench comprising: a rotatable shaft, motor means forrotating said shaft, an eccentrically disposed projection, parallel toand extending from an end of said shaft, a ball having an openingtherein in which said stud is rotatably received, an oscillatory headhaving a circular opening disposed at its center of rotation and teethcarried about the periphery of said opening, said head having an arcuateslot running transverse the direction of oscillation, said ball beingcarried in said slot, a frame, a rotatably wrench drive journalized insaid frame, springloaded pawl means carried by said wrench drive, saidpawl means being engageable with said teeth on said oscillatory headwhen said teeth are moving in one direction but disengageable from saidteeth when said teeth are moving in the opposite direction, and meansfor placing a restrictive force on said wrench drive to provide ratchetaction When said wrench drive is not carrying a substantial load, saidopening in said ball being eccentrically located with respect, to thediameter of said ball.

6. A power wrench comprising: a rotatable shaft, motor means forrotating said shaft, an eccentrically disposed projection, parallel toand extending from an end of said shaft, a ball having an openingtherein in which said stud is rotatably received, an oscillatory headhaving a circular opening disposed at its center of rotation and teethcarried about the periphery of said opening, said head having an arcuateslot Iunning transverse the direction of oscillation, said ball beingcarried in said slot, a frame, a rotatable wrench drive journalized insaid frame, spring-loaded pawl means carried by said Wrench drive, saidpawl means being engageable with said teeth on said oscillatory headwhen said teeth are moving in one direction but disengagable from saidteeth when said teeth are moving in the opposite direction, means forplacing a restrictive force on said wrench drive to provide ratchetaction when said Wrench drive is not carrying a substantial load, saidmeans for placing a resistive force on said wrench drive means comprisecompressible means for transmitting a force from said frame to saidwrench drive means, and said opening in the said ball beingeccentrically located with respect to the diameter of said ball.

7. The combination of power transmission mean and a driven membercomprising: a rotatable shaft, an eccentrically disposed member carriedby said shaft, actuator means rotatably, eccentrically mounted withrespect to said member, a driven member rotatably supported to adapt itfor oscillation about an axis, and means drivingly connecting saiddriven member to said actuator means for varying the amount of strokeand the force transmitted to said driven member in dependence upon theload applied to said driven member.

8. The power wrench of claim 1 and further comprising means for placinga resistive force on said wrench drive during oscillation of said headwhereby rotation of said wrench drive will occur When said Wrench driveis not carrying a substantial load.

9. A power wrench comprising a rotatable drive shaft, means operativelyassociated with said drive shaft for rotation thereof, a rotatablewrench drive, eccentric means on said drive shaft, actuator meansdrivingly connected with said eccentric means on said drive shaft, andoscillating head means drivingly connected with said actuator means andwrench drive for rotating said wrench drive with a progressively varyingtorque force depending upon the load applied to aid wrench drive, meansdrivingly interconnecting said oscillating head means and wrench driveimparting intermittent uni-directioal rotation to said wrench drive,said means drivingly interconnecting said oscillating head means andwrench drive including reversible means imparting rotation to saidwrench drive in a selected rotational direction.

10. The power wrench as defined in claim 9 wherein said reversible meansincludes a reversible ratchet assembly interconnecting the wrench driveand oscillating head means, and means placing a resistive force on saidwrench drive to assure uni-directional rotation of the wrench driveduring oscillation of the oscillating head means.

11. The power wrench as defined in claim 10 wherein said ratchetassembly includes an internal ratchet gear with inwardly facing teethfixed in relation to the oscillating head means, pawl means carried bysaid wrench drive and disposed within the internal gear and engaging theteeth on the gear when the gear and oscillating head means are moving inone direction but disengaging therefrom when said teeth are moving inthe other direction,

.spring loaded means carried. by said Wrench drive and movably engagedwith said pawl means for selective movement between two positions forchanging the direction of movement of said teeth in which said pawlmeans engage said teeth, and a projection connected to said springloaded means and extending exteriorly of the wrench drive andoscillating head means for manual manipulation thereof to determine thedirection of rotation of said wrench drive independently from thedirection of rotation of said drive shaft.

12. The power wrench as defined in claim 11 wherein said pawl meansincludes an arcuate elongated pawl member having arcuate inner and outeredges oriented generally concentrically with the internal gear, ratchetteeth on the end regions of the outer edge of the pawl member, shaftmeans at the central region of said pawl member rockably supporting thepawl member from the wrench drive to enable the ratchet teeth atselective end regions of the pawl member to be engaged with the internalgear teeth, said spring loaded means including a rotatable cylindricalmember journaled in the wrench drive, a plunger slidably received in adiametric bore in said cylindrical member, said plunger including aradially extending end portion engaging the arcuate inner edge of saidpawl member, spring means biasing said plunger radially outwardly forrocking said pawl member about the shaft means when the cylindricalmember is rotated to shift the plunger from one side of the shaft meansto 8 c the other, said projection being in the form of a knob rigid withsaid cylindrical member for manually reversing the ratchet assembly.

13. A self-contained portable power ratcheting wrench comprising ahousing with a substantially circular end member and an elongated handlemember, a shaft and power rotor journalled in said elongated handlemember, said shaft extending from said elongated handle member into saidsubstantially circular end member, a substantially circular head mountedfor oscillatory rotary movement in said circular housing end member,said circular oscillatory head having a circular interior openingtherein concentric with the axis of rotary movement thereof in saidhousing end member for to-and-from movement relative thereto, an annularseries of ratchet teeth on the circumference of said oscillatory headinterior opening, a work engaging member mounted for rotary movement inthe circular opening of said head, pawl means movably mounted on saidwork engaging member to confront and react with said annular series ofratchet teeth responsive to the to-and-fro rotary movement of saidoscillatory head, and complemental interconnecting eccentric meansbetweeen the end of said power rotatable shaft and said oscillatory headto move the latter to-and-fro responsive to the continuous rotation ofsaid shaft, thereby imparting unidirectional ratcheting movement to saidwork engaging member, said eccentric means including an eccentricallypositioned pin on the end of said shaft and a ball eccentrically mountedwith respect to its own diameter on said pin for varying the ratchetingstroke and the force transmitted to said work engaging member in inverseratio to the turning load thereon.

References Cited UNITED STATES PATENTS 3,167,936 2/1965 Engquist 64293,106,274 10/1963 Madsen 64-29 X 3,024,682 3/1962 Finkle 8l52.43,205,985 9/1965 Pearl 8l52.4 X 2,826,107 3/1958 Woods 8l52.4

JAMES L. JONES, in, Primary Examiner US. 01. X.R.

